The translation of acoustical energy from a high intensity, low frequency fluidborne sound source to a high static pressure piping system is now performed by use of an acoustical projector device involving exposure of a piston to gas and liquid under balanced pressure, as disclosed in the aforementioned prior copending patent application. However, in order to insure signal quality of the sound translated to the piping system, air bubbles must be periodically removed from the fluid through which the sound is being translated. To do so, the aforementioned type of acoustic projector device had to be periodically disassembled from its system for removal of air bubbles and to undergo testing, involving a considerable loss of time and imposition of labor costs. It is therefore an important object of the present invention to provide a modified version of the aforementioned type of acoustic projector device which accommodates selective operation for air bubble removal purposes without disassembly from the associated sound translation system.
In accordance with the present invention, the aforementioned type of acoustic projector device has a T-shaped housing within which a piston chamber enclosing sleeve is disposed extending axially between a sound source shaker input on a piston rod extending from a piston within the sleeve and a liquid output to the piping system. A sweeping flow of pressurized liquid such as water is selectively supplied through a valve to the housing, intermediate the shaker input and the output end of the sleeve to form a sweep chamber in surrounding relation to such piston chamber enclosing sleeve for discharge of air through a housing vent during a deaerating process. Fluid communication between such sweep chamber and the piston chamber is established during such process when the piston is displaced under system pressure control from its acoustically ideal position within the sleeve for performing the sound translating operation. Toward that end, axially extending slots are formed in the piston chamber enclosing sleeve at a location covered by the piston in its acoustically ideal position in close adjacency to one of two extreme positions between which displacement of the piston is mechanically limited by stops mounted on the piston rod.